(1) Field of the Invention
The present invention relates to a combined output and drive circuit for a mass flow transducer such as a Coriolis type mass flow transducer.
(2) Description of the Prior Art
Example of Coriolis type transducers are described in GB-A Nos. 2 202 631, 2 192 714 and 2 212 613. The details of such transducers form no part of the present invention. It is sufficient to know that a vibrating tube is driven at its resonant frequency by a drive signal applied to a drive coil or other transducer, e.g., piezoelectric, and has two spaced pick-up coils or other transducers, e.g., optical pick-ups. The mass flow rate in the tube is a linear function of the ratio of the phase difference between the two signals provided by the pick-up coils to the resonant frequency.
The data provided by such transducers will commonly form the basis for charging for bulk supplies of fluids flowing in pipelines, and there is a need to ensure that measurements are extremely accurate. A relatively small error can translate into a large sum of money in the charge for bulk supplies.